Evaluating the Lithospheric Structure and Regional/Residual Bouguer Anomalies in Peninsular India Through Potential Field Modeling and Thermal Analysis

Abstract

The Indian lithospheric mantle has been deeply influenced by geological processes such as rifting, plume activity, and collision-subduction events. Therefore, it is vital to understand the genesis of the Indian continental lithosphere and its eventual destruction by intraplate tectonic processes. The present study provides an integrated perspective of the crust and lithospheric mantle of the Indian peninsula and surrounding regions, derived from the combined modeling of topography data and geoid anomalies, constrained by seismic observations. The method involves local isostasy with a temperature-dependent density in the lithospheric mantle. The seismic Moho depth data of 361 data points from receiver functions (RFs) and deep seismic sounding (DSS) have been utilized in the modeling procedure. Crustal thickness across the region varies between 34 and 70 km, while the lithosphere-asthenosphere boundary (LAB) depth ranges from 140 to 250 km, with the maximum depths located beneath the Indo-Gangetic Plain. In contrast, the southern Indian shield exhibits an average LAB depth of approximately 170 km. Additionally, a gradual increase in LAB depth from western to eastern Dharwar has been observed, which may correspond to the combined influences of plume activity and thermo-chemical erosion associated with extensive metasomatism over time. Furthermore, lateral variations in crustal density are examined through residual gravity anomalies, revealing notable gravity lows in sediment-rich regions such as the Ganga and Godavari basins, along with pronounced positive anomalies in areas characterized by dense rock formations.